On Nov 30, 2011, at 4:18 PM, Ian Lance Taylor wrote: > Amittai Aviram <amittai.aviram@xxxxxxxx> writes: > >> What does the ".value" directive mean and what is it for? The assembly code I'm looking at is for x86_64, if that makes a difference. Thanks! > > > It puts a two byte value into the output section. E.g., > > short x = 1; > > might generate > > x: > .value 1 > > Ian Thanks, Ian. I don't quite follow your example--I would have expected short x = 1; to result in something like push $1 with the stack pointer at the appropriate address. But, looking at the objdump disassembly of my code, I think I can see what you mean. The two-byte value is simply written into the code at that point as the next instruction. In this case, the value is 0x0f0b, which is, indeed, the "invalid opcode" instruction (UD2), and makes sense in this context as a low-level exception mechanism. Amittai Aviram PhD Student in Computer Science Yale University 646 483 2639 amittai.aviram@xxxxxxxx http://www.amittai.com
